Antiretroviral Pregnancy Registry finds no increase in congenital anomalies with exposure to tenofovir

The Antiretroviral Pregnancy Registry (APR) is a prospective registry, based in the US, to detect teratogenic effects in infants exposed to maternal antiretroviral therapy. The APR collects data through voluntary reporting from health care providers.

The registry receives reports on approximately 900 pregnant women receiving antiretrovirals each year (approximately 14% of live infants born to HIV-positive women) and has operated since January 1, 1989. It has received information on sufficient numbers of first trimester exposures to 11 antiretrovirals including AZT and TDF to detect at least a 1.5- and 2-fold increase in overall birth defects respectively.

A poster from Olmsheid and Zhang showed that, as of July 31 2007, among 8483 prospective cases reported to the APR, there has been no overall increase in congenital anomalies in infants following any first or second/third trimester antiretroviral exposure compared to the general population. [1]

The authors report that the prevalence of anomalies with any antiretroviral exposure in the first trimester was 2.8/100 live births (95% CI: 2.2-3.5) [74/2673]; with 2nd/3rd trimester exposure 2.6/100 live births (2.1-3.1) [109/4220].

The prevalence of anomalies with first trimester exposure to TDF was 1.6% (0.6-3.4) [6/380] and with 2nd/3rd trimester exposure the prevalence was 1.5% (0.4-3.9) [4/263]. There was no specific pattern of anomalies reported. The prevalence of anomalies with first trimester exposure to AZT was 2.9% (2.2-3.8) [53/1816] and with 2nd/3rd trimester exposure, 2.7% (2.2-3.2) [121/4491].

The authors note that these rates are comparable to those from the CDC population-based birth defects surveillance system(2.7/100 live births).

They write: “To date no increase in prevalence of or any specific pattern of congenital anomalies has been seen with use of TDF in 643 live births through prospective voluntary reporting to the APR.”

Comment

The most recent data cut (July 08) now available on their website (www.apregistry.com) was able to report over 200 cases of first trimester atazanavir exposures. This provides adequate numbers to detect a potential 2-fold increase in birth defects altogether (at 80% power) – a finding was not seen.

Olmscheid B. and Zhang S. Use of tenofovir disoproxil fumarate (TDF) in pregnancy: Findings from the Antiretroviral Pregnancy Registry (APR). 48th ICAAC, 25-28 October 2008. Washington. Abstract H-456.